President Obama will speak primarily about the economy in his address to a joint session of Congress.

WASHINGTON (CNN) - The latest draft of President Obama's first address to a joint session of Congress is running between 50 and 60 minutes, according to two senior aides.

Aides say the speech, which will have a heavy focus on the economy, will try and strike an optimistic tone. That's a sign Obama has heard the criticism, including from former President Bill Clinton, that he needs to mix sober talk with an upbeat bottom line.

"He believes we will meet these challenges and lift ourselves out of this," one top aide said of the recession. "He will say, 'The best days are ahead of us.'"

The aides said foreign policy will be touched on lightly in the speech so that the president can focus largely on the economy and related issues, including health care, education, and energy.

Aides stressed the speech will be "thematic" and thus will not get into much detail on the president's plans to deal with the credit crunch and housing crisis.

The broad theme will be that the country needs to look forward and not backward to solve the financial crisis, according to the aides.

Obama will lay out the economic challenges he has been discussing in recent weeks and suggest many people will have to sacrifice in order to dig out of the problems, a theme he hit Monday at a fiscal responsibility summit he hosted at the White House.

One of the aides said he "will build on the need to make sure we begin to make tough choices" to deal with the $1.3 trillion annual budget deficit currently burying the federal government in debt.